diff --git a/TODO.org b/TODO.org
index dc04cfcd1..4d19d1046 100644
--- a/TODO.org
+++ b/TODO.org
@@ -89,7 +89,7 @@
     + [ ] twitter
     + [ ] present
 
-** 2.0.3 [22/42]
+** 2.0.3 [23/46]
 + [ ] Test ~package-autoremove~
 + [ ] tools/upload: add ~+upload/open-remote-file~ command to open current file
       on the remote (with TRAMP)
@@ -104,16 +104,21 @@
 + [ ] Write ~describe-setting~ for ~def-setting!~ definitions.
 + [ ] Fix invisible buffer-info segment in modeline for terminal Emacs
 + [ ] ui/doom-modeline: fix ~0/0~ display in modeline (leftover anzu state)
-+ [1/9] New module :: tools/regex (PCRE IDE)
++ [2/13] New module :: tools/regex (PCRE IDE)
   + [X] perl backend
-  + [ ] replace support
-  + [ ] export to code support
-  + [ ] python exporter (use ~re~ or ~regex~)
-  + [ ] php exporter (~preg_(match(_all)?|replace)~)
-  + [ ] ruby backend (~%r[.+]~)
-  + [ ] javascript (node) backend (~/.+/~)
+  + [X] replace support
+  + [-] highlight replaced segments
+  + [0/7] export-to-code feature
+    + [ ] search+replace support
+    + [ ] python exporter (use ~re~ or ~regex~)
+    + [ ] php exporter (~preg_(match(_all)?|replace)~)
+    + [ ] ruby exporter (~%r[.+]~)
+    + [ ] javascript (node) exporter (~/.+/.test(...)~)
+    + [ ] C exporter (~regex.h~ + ~regcomp~)
+    + [ ] C++ exporter (~regex reg(regexp, ...)~)
   + [ ] syntax highlighter for ~+regex-mode~ (plus make it a major mode)
   + [ ] README.org
+  + [ ] Use ~make-process~ daemon approach rather than ~call-process~
 + [X] ui/doom: fix nav-flash on evil-multiedit or in eshell/term buffers
 + [X] core-os: don't use GTK tooltips (ugly!)
 + [X] ui/doom-modeline: reduce excess whitespace on right of flycheck segment
diff --git a/modules/app/regex/autoload/regex.el b/modules/app/regex/autoload/regex.el
index b6912802c..0a994c26a 100644
--- a/modules/app/regex/autoload/regex.el
+++ b/modules/app/regex/autoload/regex.el
@@ -1,22 +1,25 @@
 ;;; app/regex/autoload/regex.el
 
 (defvar +regex--text-buffer nil)
+(defvar +regex--text-replace-buffer nil)
 (defvar +regex--expr-buffer nil)
+(defvar +regex--expr-replace-buffer nil)
 (defvar +regex--groups-buffer nil)
+(defvar +regex--replace-buffer nil)
 
 ;;
 (defface +regex-match-0-face
-  '((t (:foreground "Black" :background "Red" :bold t)))
+  `((t (:foreground "Black" :background ,(doom-color 'magenta) :bold t)))
   "TODO"
   :group 'doom)
 
 (defface +regex-match-1-face
-  '((t (:foreground "Black" :background "Blue" :bold t)))
+  `((t (:foreground "Black" :background ,(doom-color 'blue) :bold t)))
   "TODO"
   :group 'doom)
 
 (defface +regex-match-2-face
-  '((t (:foreground "Black" :background "Green" :bold t)))
+  `((t (:foreground "Black" :background ,(doom-color 'green) :bold t)))
   "TODO"
   :group 'doom)
 
@@ -27,9 +30,13 @@
 ;;
 (defvar +regex-mode-map
   (let ((map (make-sparse-keymap)))
-    (evil-define-key* 'normal map
-      "\C-c\C-c" #'+regex-update-buffers
-      "\C-c\C-k" #'+regex/quit)
+    (define-key map "\C-c\C-c" #'+regex-update-buffers)
+    (define-key map "\C-c\C-r" #'=regex/replace)
+    (define-key map "\C-c\C-k" #'+regex/quit)
+    (define-key map [remap doom-kill-buffer]      #'+regex/quit)
+    (define-key map [remap doom/kill-this-buffer] #'+regex/quit)
+    (define-key map [remap kill-this-buffer]      #'+regex/quit)
+    (define-key map [remap kill-buffer]           #'+regex/quit)
     map)
   "TODO")
 
@@ -48,75 +55,119 @@
 (defun =regex (&optional dummy-text)
   "Start the Regex IDE."
   (interactive "P")
-  (condition-case ex
-      (progn
-        (setq +regex--expr-buffer (get-buffer-create "*doom-regex*")
-              +regex--text-buffer (if dummy-text (get-buffer-create "*doom-regex-text*") (current-buffer))
-              +regex--groups-buffer (get-buffer-create "*doom-regex-groups*"))
-        (when dummy-text
-          (+workspace-switch +regex-workspace-name t)
-          (switch-to-buffer +regex--text-buffer)
-          (insert +regex-dummy-text))
-        (doom-popup-buffer +regex--groups-buffer)
-        (doom-popup-buffer +regex--expr-buffer)
-        (with-current-buffer +regex--expr-buffer
-          (conf-mode)
-          (rainbow-delimiters-mode +1)
-          (linum-mode -1)
-          (+regex-mode +1)
-          (text-scale-set 3)))
-    ('error
-     (+regex/quit)
-     (error "Failed to open the Regexp IDE: %s" ex))))
+  (unless (buffer-live-p +regex--expr-buffer)
+    (condition-case ex
+        (progn
+          (setq +regex--expr-buffer (get-buffer-create "*doom-regex*")
+                +regex--text-buffer (if dummy-text (get-buffer-create "*doom-regex-text*") (current-buffer))
+                +regex--groups-buffer (get-buffer-create "*doom-regex-groups*"))
+          (when dummy-text
+            (+workspace-switch +regex-workspace-name t)
+            (switch-to-buffer +regex--text-buffer)
+            (with-current-buffer +regex--text-buffer
+              (insert +regex-dummy-text)))
+          (doom-popup-buffer +regex--groups-buffer)
+          (doom-popup-buffer +regex--expr-buffer)
+          (with-current-buffer +regex--expr-buffer
+            (conf-mode)
+            (rainbow-delimiters-mode +1)
+            (linum-mode -1)
+            (setq-local require-final-newline nil)
+            (+regex-mode +1)
+            (text-scale-set 3)))
+      ('error
+       (+regex/quit)
+       (error "Failed to open the Regexp IDE: %s" ex)))))
+
+;;;###autoload
+(defun =regex/replace ()
+  (interactive)
+  (unless (buffer-live-p +regex--replace-buffer)
+    (let (text)
+      (=regex t)
+      (with-selected-window (get-buffer-window +regex--text-buffer)
+        (setq text (buffer-string))
+        (select-window (split-window-right))
+        (switch-to-buffer (get-buffer-create "*doom-regex-text-repl*"))
+        (erase-buffer)
+        (insert text)
+        (read-only-mode +1)
+        (setq +regex--text-replace-buffer (current-buffer)))
+      (with-current-buffer +regex--expr-buffer
+        (select-window (split-window-right))
+        (switch-to-buffer (get-buffer-create "*doom-regex-repl*"))
+        (conf-mode)
+        (rainbow-delimiters-mode +1)
+        (linum-mode -1)
+        (setq-local require-final-newline nil)
+        (setq mode-line-format nil
+              +regex--expr-replace-buffer (current-buffer))
+        (+regex-mode +1)
+        (text-scale-set 3)))))
 
 ;;;###autoload
 (defun +regex/quit ()
   "TODO"
   (interactive)
-  (kill-buffer +regex--expr-buffer)
-  (kill-buffer +regex--groups-buffer)
   (when (and +regex--text-buffer (buffer-live-p +regex--text-buffer))
     (with-current-buffer +regex--text-buffer
       (+regex-mode -1)
-      (remove-overlays)))
-  (setq +regex--expr-buffer nil
-        +regex--text-buffer nil
-        +regex--groups-buffer nil)
+      (remove-overlays nil nil 'category '+regex))
+    (when (equal (buffer-name +regex--text-buffer) "*doom-regex-text*")
+      (kill-buffer +regex--text-buffer)))
   (when (equal (+workspace-current-name) +regex-workspace-name)
-    (kill-buffer +regex--text-buffer)
-    (+workspace/delete +regex-workspace-name)))
+    (+workspace/delete +regex-workspace-name))
+  (mapc (lambda (bufname)
+          (let ((buf (symbol-value bufname)))
+            (when (and buf (buffer-live-p buf))
+              (kill-buffer buf)
+              (set bufname nil))))
+        (list '+regex--text-replace-buffer
+              '+regex--expr-replace-buffer
+              '+regex--expr-buffer
+              '+regex--groups-buffer
+              '+regex--replace-buffer)))
+
+(defun +regex--expr ()
+  (when (buffer-live-p +regex--expr-buffer)
+    (with-current-buffer +regex--expr-buffer
+      (string-trim (buffer-string)))))
+
+(defun +regex--expr-replace ()
+  (when (buffer-live-p +regex--expr-replace-buffer)
+    (with-current-buffer +regex--expr-replace-buffer
+      (string-trim (buffer-string)))))
 
 ;;;###autoload
 (defun +regex-update-buffers (&optional beg end len)
   (interactive)
-  (let ((regex (with-current-buffer +regex--expr-buffer (buffer-string))))
-    (when (> (length regex) 0)
-      (with-current-buffer +regex--groups-buffer
-        (erase-buffer))
-      (with-current-buffer +regex--text-buffer
-        (remove-overlays)
+  (let* ((inhibit-read-only t)
+         (regex (or (+regex--expr) ""))
+         (replace (or (+regex--expr-replace) ""))
+         (str (or (with-current-buffer +regex--text-buffer (buffer-string)) "")))
+    (with-current-buffer +regex--groups-buffer
+      (erase-buffer))
+    (with-current-buffer +regex--text-buffer
+      (remove-overlays nil nil 'category '+regex)
+      (when (> (length regex) 0)
         (save-excursion
-          (ignore-errors
-            (goto-char (point-min))
-            (pcase +regex-default-backend
-              ('emacs        (+regex-backend-emacs regex))
-              ('perl         (+regex-backend-generic (+regex-backend-perl regex)))
-              ('python       (+regex-backend-generic (+regex-backend-python regex)))))))
-      (with-current-buffer +regex--groups-buffer
-        (goto-char (point-min))))))
+          (goto-char (point-min))
+          (pcase +regex-default-backend
+            ('emacs (+regex-backend-emacs regex replace str))
+            ('perl  (+regex-backend-perl regex replace str))))))
+    (with-current-buffer +regex--groups-buffer
+      (goto-char (point-min)))))
 
 
 ;; --- backends ---------------------------
 
-(defun +regex--backend-perl (regex sample)
+(defun +regex--render-perl (regex text)
   "From <https://github.com/jwiegley/regex-tool>"
   (with-temp-buffer
-    (unless (string-match-p "^/.+/[gm]*$" regex)
-      (setq regex (concat "/" regex "/g")))
     (insert (format "@lines = <DATA>;
 $line = join(\"\", @lines);
 print \"(\";
-while ($line =~ m%smg) {
+while ($line =~ m/%s/gm) {
   print \"(\", length($`), \" \", length($&), \" \";
   for $i (1 .. 20) {
     if ($$i) {
@@ -129,53 +180,95 @@ while ($line =~ m%smg) {
 }
 print \")\";
 __DATA__
-%s" regex sample))
+%s" (replace-regexp-in-string "/" "\\/" regex nil t) text))
     (call-process-region (point-min) (point-max) "perl" t t)
     (goto-char (point-min))
     (read (current-buffer))))
 
+(defun +regex--replace-perl (regex replace text)
+  (unless (or (string-empty-p regex)
+              (string-empty-p replace)
+              (string-empty-p text))
+    (with-temp-buffer
+      (insert (format "@lines = <DATA>;
+$line = join(\"\", @lines);
+$line =~ s/%s/%s/gm;
+print $line;
+__DATA__
+%s" (replace-regexp-in-string "/" "\\/" regex nil t) (replace-regexp-in-string "/" "\\/" replace nil t) text))
+      (call-process-region (point-min) (point-max) "perl" t t)
+      (buffer-string))))
+
 ;;;###autoload
-(defun +regex-backend-perl (regex)
+(defun +regex-backend-perl (regex replace str)
   "TODO"
-  (let ((results (+regex--render-perl regex (buffer-string)))
-        (i 0))
-    (dolist (result results)
-      (let ((offset (nth 0 result))
-            (length (nth 1 result))
-            (matches (nthcdr 2 result)))
-        (overlay-put (make-overlay (1+ offset) (+ offset length 1))
-                     'face (nth (mod i 3) +regex-faces))
+  (cl-assert (stringp regex))
+  (cl-assert (stringp replace))
+  (cl-assert (stringp str))
+  (let ((i 0)
+        (results (+regex--render-perl regex str)))
+    (when (buffer-live-p +regex--text-replace-buffer)
+      (let ((replace (+regex--replace-perl regex replace str)))
+        (with-current-buffer +regex--text-replace-buffer
+          (erase-buffer)
+          (insert
+           (if (and (listp results)
+                    replace
+                    (not (string-empty-p replace)))
+               replace
+             str)))))
+    (dolist (result (if (listp results) results))
+      (let* ((offset (nth 0 result))
+             (length (nth 1 result))
+             (matches (nthcdr 2 result))
+             (ov (make-overlay (1+ offset) (+ offset length 1))))
+        (overlay-put ov 'face (nth (mod i 3) +regex-faces))
+        (overlay-put ov 'category '+regex)
         (cl-incf i)
-        (let ((match-zero (buffer-substring (1+ offset) (+ offset length 1))))
+        (let* ((match-zero (buffer-substring (1+ offset) (+ offset length 1)))
+               (line (format "Match: %s\n" (propertize match-zero 'face 'font-lock-string-face))))
           (with-current-buffer +regex--groups-buffer
-            (insert (format "Group 0: '%s'\n" match-zero))))
+            (insert line)))
         (dolist (match matches)
           (with-current-buffer +regex--groups-buffer
             (goto-char (point-max))
-            (insert (format "Group %d: '%s'\n" (car match)
-                            (cdr match)))))
+            (insert (format "Group %d: %s\n"
+                            (propertize (car match) 'face 'font-lock-constant-face)
+                            (propertize (cdr match) 'face 'font-lock-string-face)))))
         (with-current-buffer +regex--groups-buffer
           (insert ?\n))))))
 
 ;;;###autoload
-(defun +regex-backend-emacs (regex)
+(defun +regex-backend-emacs (regex replace str)
   "TODO"
+  (cl-assert (stringp regex))
+  (cl-assert (stringp replace))
+  (cl-assert (stringp str))
   (let ((i 0)
         pos)
+    (when (buffer-live-p +regex--text-replace-buffer)
+      (with-current-buffer +regex--text-replace-buffer
+        (erase-buffer)
+        (insert str)
+        (when (and (listp results) (string-empty-p replace))
+          (replace-regexp regex replace))))
     (while (and (setq pos (point))
                 (re-search-forward regex nil t))
       (if (= (point) pos)
           (forward-char 1)
-        (overlay-put (make-overlay (match-beginning 0)
-                                   (match-end 0))
-                     'face (nth (mod i 3) +regex-faces))
+        (let ((ov (make-overlay (match-beginning 0) (match-end 0))))
+          (overlay-put ov 'face (nth (mod i 3) +regex-faces))
+          (overlay-put ov 'category '+regex))
         (cl-incf i)
         (dotimes (i 10)
           (when-let (text (match-string i))
             (save-match-data
               (with-current-buffer +regex--groups-buffer
                 (goto-char (point-max))
-                (insert (format "Group %d: '%s'\n" i text))))))
+                (insert
+                 (format "Group %d: %s\n"
+                         (propertize i    'face 'font-lock-constant-face)
+                         (propertize text 'face 'font-lock-string-face)))))))
         (with-current-buffer +regex--groups-buffer
           (insert ?\n))))))
 
diff --git a/modules/app/regex/config.el b/modules/app/regex/config.el
index 17ab21474..cc073013b 100644
--- a/modules/app/regex/config.el
+++ b/modules/app/regex/config.el
@@ -47,6 +47,6 @@ https://mediatemple.net"
   "TODO")
 
 (set! :popup
-  '("*doom-regex*" :size 4 :select t :noesc t :autokill t)
-  '("*doom-regex-groups*" :align left :size 30 :noselect t :noesc t :autokill t))
+  '("*doom-regex*" :size 4 :select t :noesc t)
+  '("*doom-regex-groups*" :align left :size 30 :noselect t :noesc t))